Mackinaw prepares lanes for upcoming shipping season

The U.S. Coast Guard broke out its big gun this past weekend, sending the Mackinaw to break ice in the Twin Ports.

The 240-foot-long ship has a beam of 58½ feet and a displacement of 3,500 long tons. It’s that sheer weight the vessel uses to great effect busting ice on the Great Lakes.

Yet this hefty ship, the largest U.S. icebreaker serving the Great Lakes, is surprisingly nimble thanks to its unique propulsion system, consisting of two powerful aft-mounted azipods, located side by side, and one bow thruster.

“This is an incredible ship, but its great crew is what makes it so special,” said Cmdr. Mike Davanzo, reflecting on the icebreaker’s full complement of 10 officers and 46 enlisted members.

Pulling out an aerial photograph taken a few days ago, Davanzo pointed to the western-most tip of Lake Superior. While much of the lake appeared ice-free, the solid white beneath his index finger told a different story for the port of Duluth-Superior.

“Most of our work for the past couple days has been out on that plate,” he said. “We’ve been cutting the ice into wedges so wind could push it out into the lake.”

The winds cooperated Saturday, although they were of more modest strength than Davanzo had hoped.

“Mother Nature is a better icebreaker than we are,” he said. “We try to manage the ice rather than just break it.”

Winds off the lake Sunday did little to help the cause, but the Mackinaw went to work nevertheless retracing a path cut earlier in the week by the smaller Coast Guard Cutter Alder, a Duluth-based vessel whose primary mission is buoy-tending.

“We’re going to widen and freshen the tracks,” Davanzo explained.

Final preparations for a new shipping season will be in high gear this week, with the Soo Locks slated to welcome its first vessel of the year on March 25.

“Winter is just as busy, but it’s a different kind of busy,” said Bill Peterson, general manager of the Great Lakes fleet, headquartered in Duluth.

Lake carriers make good use of the brief winter layup to tackle needed repairs and maintenance, hoping their fleets won’t miss a beat once the shipping season begins. But those efforts take on a new intensity in the final days of fitting out. He said the Great Lakes Fleet’s nine vessels employ about 225 people.

As usual, most of the fleet will get off to a quick start this year, but due to soft market conditions, the John G. Munson will remain moored at the dock until its services are required.

Most of the ice the Mackinaw encountered in and around the Twin Ports this weekend was of the 20-some-inch-thick variety — well within its capabilities. The $80 million ship was designed to move handily through 32-inch ice at a steady 3-knot pace and to ram its way through ridge ice up to 10 feet thick.

The heavily reinforced ship is equally capable of making its way through thick ice with its bow or stern.

The Mackinaw also can break ice by using its powerful and unique propulsion system. It demonstrated this capability Sunday morning alongside the Canadian National/DM&IR ore dock.

The Mackinaw has a pair of Azipod propulsion units that can turn 360 degrees. By pointing its starboard and port Azipods in opposing directions and using the wash, it made quick work of ice near the dock Sunday, pushing water over the top of the ice and causing it to buckle. The maneuver about tripled the width of a track the ship had already cut.

Lt. Stephen Elliott said the technique uses a lot of fuel but has its place.

“We use it when we’re next to a pier in a restricted harbor, where we don’t want to risk any structural damage, and when we’re close to a ship that’s beset in ice,” he said.

The Mackinaw completed its work in the Twin Ports on Sunday morning and set out for its next assignment in Whitefish Bay before noon.

“So many different areas still need our attention,” said Lt.j.g. Katie Braynard, describing the busy itinerary the ship will keep in the coming weeks, as it busts out ports and tackles problem “choke points” in the St. Marys River.

A small crowd of well-wishers gathered behind the Duluth Entertainment Convention Center late Sunday morning to see the Mackinaw off.

The modest throng put a smile on Cmdr. Davanzo’s face.

“What’s really neat about working on the Great Lakes is that people here are so appreciative of the work we do,” he said.

Tags: lake superior, twin ports, news, business, shipping